Explanation of Prepare clear input file

[babinyurii]

Currently when the input doesn't start with reading frame, your tool throws an exception: Your file contains invalid codons.

It can confuse an inexperienced user.

I would suggest the following options:
1 you can add into the readme an explanation of how to prepare the input file
2 you can improve the raised message and make it more clear so that user understands how to fix the input

I believe this is currently in the line 247 raise Exception("Your file contains invalid codons.")

[babinyurii]

Ок. I close the issue.